Letter abstract
Nature Materials 5, 467 - 470 (2006)
doi:10.1038/nmat1649
Subject Categories: Polymers | Design synthesis and processing
Photocontrolled living polymerizations
Makoto Tanabe1,3, Guido W. M. Vandermeulen1,4, Wing Yan Chan1, Paul W. Cyr1, Lawrence Vanderark1, David A. Rider1 and Ian Manners1,2
Living polymerizations involve the creation of polymer chains without significant irreversible chain transfer or chain termination1. Such processes are widely used to access well-defined macromolecular materials with controlled architectures, such as block and star polymers. Although this concept was first realized for anionic polymerizations in the 1950s2, many key recent advances have been made, most notably in the area of radical polymerization3, 4, 5, 6. Here, we report a living photopolymerization that involves photoexcited monomers. Exposure of metal-containing ferrocenophane monomers to Pyrex-filtered light from a mercury lamp (
>310 nm) or to bright sunlight in the presence of an anionic initiator leads to living polymerizations, in which the conversion and molecular weight of the resulting polymer can be controlled by the irradiation time. Photoirradiation selectively weakens the iron–cyclopentadienyl bond in the monomer, allowing the use of moderately basic and highly functional-group-tolerant initiators. The polymerization proceeds through attack of the initiator and propagating anion on the iron atom of the photoexcited monomer and, remarkably, the polymerization rate decreases with increasing temperature. Block copolymer formation is possible when the light source is alternately switched on and off in between sequential addition of different monomers, providing unprecedented, photocontrolled access to new types of functional polymers.
- Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
- School of Chemistry, University of Bristol, Bristol BS8 1TS, UK
- Present address: Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
- Present address: BASF AG, Research Solution Polymers, 67056 Ludwigshafen, Deutschland
Correspondence to: Ian Manners1,2 e-mail: Ian.Manners@Bristol.ac.uk
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